This invention relates to a digital signal recording apparatus for analog/digital input, and more particularly is suitable for use with a digital recording/reproducing apparatus.
In a conventional digital recording/reproducing apparatus, e.g. a digital audio tape recorder (DAT), digital audio signals to be inputted are digital-recorded on a magnetic tape. In addition, there are two series of signal input terminals so that analog audio signals to be inputted are converted into digital audio signals and digital-recorded on the magnetic tape.
Besides, in the DAT, there are two series of signal output terminals so that the digital audio signals obtained by reproducing from the magnetic tape are outputted directly and the digital audio signals are converted into analog audio signals and outputted.
In particular, the digital audio signals are digital-recorded on the magnetic tape and simultaneously, after being reproduced therefrom, outputted as digital audio signals. In this case, there is no decline in sound quality of the audio signals in terms of utilization. Ideally, the audio signals can be recorded and reproduced.
Where the audio signals are ideally recorded and reproduced, it follows that transcriptional recording, i.e., so-called dubbing, can be repeated any number of times. This conduces to a possibility in which the author's copyright is infringed. Hence, there is a serial copy management system (SCMS) adapted to effect generation management of copies of the digital audio signals as a method of managing and restricting the infringement.
To be specific, 2-bit digital copy authorized information is contained in the subcodes added to the digital audio signal inputted to the DAT from the digital signal source such as the DAT, the compact disc unit and the satellite broadcasting transmitter/receiver. As a matter of fact, 2 bits of the digital copy authorized information serve to specify a status of whether the digital copy is authorized over any generations or only one generation or is inhibited.
Hence, in the DAT, the digital copy authorized information of the subcodes added to the digital audio signals to be inputted specify the extent to which the copying is authorized over any generations. Then, the digital audio signals are digital-recorded on the magnetic tape and at the same time recorded as subcode data by setting the status in which the digital copy is authorized over any generations as new digital copy authorized information.
When the digital copy authorized information added to the digital audio signals to be inputted specifies the status in which the digital copy is authorized over only one generation, the digital audio signals are digital-recorded on the magnetic tape and at the same time recorded as subcode data by setting the status in which the digital copy is inhibited as new digital copy authorized information.
Further, when the digital copy authorized information added to the digital audio signals to be inputted specify the status in which the digital copy is inhibited, the digital record of the digital audio signals is immediately stopped.
Incidentally, as illustrated in FIG. 1, there has been proposed a so-called DAT system 1 structured by combining the DAT described above with a module consisting of sources of various audio signals. For instance, in this case, the system incorporates a digital signal reproducing apparatus (DAT) 2, a compact disc unit (CD) 3 and a satellite broadcasting transmitter/receiver (BS) 4 as sources of the audio signals.
Output digital audio signals D1, D2 and D3 and output analog audio signals A1, A2 and A3 are transmitted from the digital signal reproducing apparatus (DAT) 2, the compact disc unit 3 and the satellite broadcasting transmitter/receiver 4 and then inputted to an amplifier/selector unit 5.
As a matter of fact, the amplifier/selector unit 5 selects any of the output digital audio signals D1, D2 and D3 and the output analog audio signals A1, A2 and A3 which are inputted from the digital signal reproducing apparatus (DAT) 2, the compact disc unit 3 or the satellite broadcasting transmitter/receiver 4 in accordance with an operation of the user. The amplifier/selector unit 5 transmits the selected signal as an input digital audio signal DIN and an input analog audio signal AIN of a digital signal recording apparatus (DAT) 6.
If it is thereby known that the digital copy is authorized by the digital copy authorized information contained in the output digital audio signal D1, D2 or D3 transmitted from the digital signal reproducing apparatus (DAT) 2, the compact disc unit 3 or the satellite broadcasting transmitter/receiver 4, the user may make a selection to record the input digital audio signal DIN by operating the digital signal recording apparatus DAT 6.
As a result of this, the output digital audio signal D1, D2 or D3 transmitted from the digital signal reproducing apparatus (DAT) 2, the compact disc unit 3 or the satellite broadcasting transmitter/receiver 4 is selected as an input digital audio signal DIN. The output digital audio signal D1, D2 or D3 is digital-recorded on the magnetic tape being composed of a signal recording medium in this manner.
Besides, if it is known that the digital copy is inhibited by the digital copy information contained in the output digital audio signal D1, D2 or D3, the user may make a selection to record the input analog audio signal DIN by operating the digital signal recording apparatus (DAT) 6.
As a consequence of this, the output analog audio signal A1, A2 or A3 transmitted from the digital signal reproducing apparatus (DAT) 2, the compact disc unit 3 or the satellite broadcasting transmitter/receiver 4 is selected as an input digital audio signal AIN. The output analog audio signal A1, A2 or A3 is digital-recorded on the magnetic tape in this way.
In the thus constructed DAT system 1, however, the user operates the digital signal recording apparatus (DAT) 6 and makes a selection to record the input digital audio signal DIN or the input analog audio signal AIN. Hence, when recording a source of such audio signals that a digital copy authorized signal portion is mixed with a digital copy inhibited signal portion, a variety of problems arise.
More specifically, as explained earlier, when recording, on the digital signal recording apparatus (DAT) 6, the output digital audio signals D1, D2 and D3 or the output analog audio signals A1, A2 and A3 which are transmitted from the digital signal reproducing apparatus (DAT) 2, the compact disc unit 3 and the satellite broadcasting transmitter/receiver 4 as the input digital audio signals DIN or the input analog audio signals AIN, the input digital audio signals DIN are recorded by operating the digital signal recording apparatus (DAT) 6. Produced in this case is a problem in which the digital copy authorized signal portion can be recorded, while recording stops at the digital copy inhibited signal portion and thereby becomes impossible.
In contrast with this, if the selection is made to record the input analog audio signal AIN by operating the digital signal recording apparatus (DAT) 6, the digital copy authorized signal portion is also recorded as the input analog audio signal AIN. This results in such a problem that the audio signal a sound quality of which declines is recorded, correspondingly.
To obviate such problems, the selection is made to, it is considered, record the input digital audio signals DIN or the input analog audio signals AIN by the user's operating the digital signal recording apparatus (DAT) 6 in accordance with the digital copy authorized and inhibited signal portions.
If done in this manner, however, and when the digital copy authorized signal portion is frequently replaced with the digital copy inhibited signal portion, troublesome switchover operations are needed correspondingly. This leads to such a problem that the usability of the user is deteriorated. Eventually, this is insufficient as a solution.
By the way, in such a DAT, there has been proposed a so-called double DAT deck 11, as in the same way with a double deck system of conventional audio tape recorders using cassette tapes, the deck 11, as illustrated in FIG. 2, being capable of dubbing from a digital signal reproducing system DAT 11A to a digital signal recording system DAT 11B. In the dubbing system, the dubbing of the signals is performed between the digital signal reproducing means and the digital signal recording means.
In the digital signal reproducing system DAT 11A of this double DAT deck 11, a magnetic tape is reproduction-driven by a mechanical-deck-structured tape driving unit 12A having a rotary head. A regenerative signal SPB obtained thereby is inputted to a digital signal processing circuit 13A.
The digital signal processing circuit 13A executes predetermined signal processing of the regenerative signal SPB. A regenerative digital audio signal DPB obtained as a result of this is transmitted to outside via a digital output terminal 14A and at the same time inputted to a digital/analog converting circuit 15A.
The digital/analog converting circuit 15A converts the regenerative digital audio signal DPB into an analog signal. This analog signal is, after being filtered by a low-pass filter 16A, transmitted as a regenerative analog audio signal APB via an analog output terminal 14B.
The regenerative digital audio signal DPB obtained in the digital signal reproducing system DAT 11A is inputted to a first input terminal a of a digital input switching circuit 17A of a dubbing switching circuit 17 provided in the digital signal recording system DAT 11B. The regenerative analog audio signal APB is inputted to a first input terminal a of the analog input switching circuit 17B of the dubbing switching circuit 17.
An input digital audio signal DIN and an input analog audio signal AIN which are provided from outside are supplied via a digital input terminal 18A and an analog input terminal 18B to second input terminals b of the digital input switching circuit 17A and the analog input switching circuit 17B.
In fact, the digital input switching circuit 17A and the analog input switching circuit 17B of this dubbing switching circuit 17 interlock with each other by an manual operation of the user. These circuits 7A, 7B serve to specify either dubbing the signal obtained from the digital signal reproducing system 11A or recording of the audio signals inputted from outside.
Either the regenerative digital audio signal DPB or the input digital audio signal DIN is selected from an output terminal of the digital input switching circuit 17A. The selected signal is inputted as a recording digital audio signal DREC to the first input terminal a of a digital/analog selection circuit 19.
Either the regenerative analog audio signal APB or the input analog audio signal AIN is selected from an output terminal of the analog input switching circuit 17B and, after undergoes filtering means of a low-pass filter 16B, inputted as a recording analog audio signal AREC to the analog/digital converting circuit 15B.
The analog/digital converting circuit 15B converts the recording analog audio signal AREC into a digital signal. A second recording digital audio signal DREC1 obtained as a consequence of this is inputted to the second input terminal b of the digital/analog selection circuit 19.
This digital/analog selection circuit 19 is capable of selecting whether an input path of a source for recording is associated with the digital audio signal DREC or the analog audio signal AREC corresponding to the manual operation of the user. A third recording digital audio signal DREC2 obtained at the output terminal thereof is inputted to a digital signal processing circuit 13B.
The digital signal processing circuit 13B executes predetermined digital signal processing of the third recording digital audio signal DREC2. A recording signal SREC obtained as a result of this is supplied to a tape driving unit 12B having a rotary head, thus digital-recording a desired audio signal on the magnetic tape.
In the double DAT deck 11, the user switches over the digital input switching circuit 17 and the analog input switching circuit 17B of the dubbing switching circuit 17 to the first input terminal a in this manner. At the same time, if it is known beforehand that the digital copy is authorized, the digital/analog selection circuit 19 is also switched over to the first input terminal a. A content reproduced by the digital signal reproducing system DAT 11A can be thereby digital-recorded by the digital signal recording system DAT 11B through a digital audio signal path LD.
If it is previously known that the digital copy is inhibited, the digital/analog selection circuit 19 is switched over to a second input terminal b. The content reproduced in the digital signal reproducing system DAT 11A can be thereby digital-recorded by the digital signal recording system DAT 11B through an analog audio signal path LA.
In the thus constructed double DAT deck 11, however, there arises a variety of problems when dubbing the magnetic tape in which a digital copy authorized signal portion is mixed with a digital copy inhibited signal portion, because the user is able to change over the dubbing path.
Namely, when dubbing the above-mentioned magnetic tape, the digital audio signal path LD is specified by selecting the first input terminal a of the digital/analog selection circuit 19. In this case, dubbing is allowed to take place at the digital copy authorized signal portion. At the digital copy inhibited signal portion, recording stops with the result that dubbing becomes impossible.
Contrastingly, the analog audio signal path LA is specified by selecting the second input terminal b of the digital/analog selection circuit 19. In this case, dubbing is effected also at the digital copy authorized signal portion via the analog audio signal path LA, and a sound quality declines correspondingly.
To obviate such problems, it is considered that the user may switch over the first input terminal a and the second input terminal b of the digital/analog selection circuit 19 by manual operation in accordance with the digital copy authorized and inhibited signal portions. If done in this way, the digital copy authorized and inhibited signal portions are frequently replaced with each other. In such a case, troublesome switching operations are required. The usability of the apparatus is deteriorated. This is insufficient as a solution.
This type of double DAT deck 11 includes the digital/analog converting circuit 15A and the analog/digital converting circuit 15B for analog signal recording and reproducing. The circuits respectively have low-pass filters 16A, 16B. On the occasion of dubbing via the analog audio signal path LA, the signals undergo filtering by the two low-pass filters 16A and 16B, and hence there is a possibility of a decline in sound quality.